1. Field of the Invention
This invention relates to anticomplementary agents comprising as the active ingredient at least one soyasapogenol B compound represented by the general formula (I): ##STR3## wherein R.sup.1 represents a hydrogen atom or a group represented by the formula: ##STR4## wherein R.sup.2 represents a hydrogen atom or a hydroxymethyl group, R.sup.3 represents a hydrogen atom or a rhamnopyranosyl group, and R.sup.4 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and pharmaceutically acceptable salts thereof.
This invention also relates to a process for preparing anticomplementary agents comprising the compound of the formul (I) or pharmaceutically acceptable salts thereof as the active ingredient.
Further, this invention relates to a process for treating nephritis. 2. Description of the Prior Art
Various compounds related to the active ingredients of the anticomplementary agents of this invention are known. For example, glycyrrhizin (Yasuhiro Ariga, Hiroyuki Sumi, Yumiko Takada and Akikazu Takada, Abridgements of Lecture Programs on Seminar of Plasmin Research Association, page 65 (1977); Koretsugu Arimoto, Kaneyuki Mineta, Hiroyuki Sumi, Yumiko Takada and Akikazu Takada, Proceedings of the 14th Symposium on Complements, pp. 79-82 (1977)) and 3-0-(6-0-methyl.beta.-D-glucuronopyranosyl)-soyasapogenol B (Isao Kitagawa, Masayuki Yoshikawa and Ichiro Yoshioka, Chem. Pharm. Bull., 22, p, 1339 (1974); Ibid., 24, p. 121 (1976)), etc., are known. The former compound has a steroid like structure and exhibits an activity similar to that of steroids. For example, it shows an inhibitory activity against plasmin, urokinase, Kallikrein, thrombin and complements. On the other hand, the physiological activities of the latter have not yet been reported. In contrast, the compounds of the formula (I) and salts thereof used in the agents of this invention have an anticomplementary activity which is unexpectedly superior to that of glycyrrhizin and which is quite unexpected from 3-0-(6-0-methyl-.beta.-D-glucuronopyranosyl)-soyasapogenol B as will be apparent from the results of pharmacological tests described hereinafter.